The present invention relates generally to the field of alignment systems, and, more particularly to alignment systems that use optics to define an alignment reference.
Today, many common power tools found in a hobbyist's workshop or basement as well as production type commercial tools come with some type of alignment guides for assisting the operator in using the tool at a desired angle. Depending on the expense of the tool, many of these alignment guides can be relatively crude requiring the operator to expend substantial time in developing a "custom" system for calculating angles and performing an alignment, such as aligning a table saw blade to make an angled cut. It is not uncommon for several practice cuts to be made before an accurate alignment is obtained.
The art is filled with examples of apparatus for aligning power tools to perform a variety of operations. For example, U.S. Pat. No. 5,121,554 to Havins discloses a miter gauge apparatus for use with conventional power saws. Havins' invention uses a protractor and a set of gages positioned about the radius of the protractor to position the saw blade physically at the correct cutting angle. A variable angle protractor is disclosed in U.S. Pat. No. 4,779,354 to Hill in which the protractor includes a reference base and a pivoting member that engages the apparatus to be aligned and moves in concert therewith to establish a desired angle of alignment.
Because of the accuracy of laser optics, several alignment systems incorporate an optic component that defines a target for the tool. U.S. Pat. No. 5,446,635 to Jehn discloses a laser assembly that projects a line of light onto a workpiece to guide a cutting instrument. Similarly, U.S. Pat. Nos. 5,285,708 and 5,375,495 to Bosten et al. disclose miter saws that use a laser to project an alignment marker on the workpiece to guide the blade.
U.S. Pat. No. 5,539,990 to Le and U.S. Pat. No. 5,594,993 to Tager et al. disclose instruments incorporating a laser for projecting reference lines for use as an alignment guide. Nevertheless, these instruments do have their shortcomings, particularly in aligning the reference line with the horizontal or vertical axis. Specifically, Le uses a plumb and support system to achieve a precise alignment with the vertical axis. Because Le's instrument must be positioned in a way that allows the plumb to hang properly, it may not be suitable for some applications in which the instrument cannot be oriented in the required configuration. The hand-held builder's tool disclosed by Tager et al. uses either a screw-thread mechanism or a cam-operated mechanism to align the reference line with a reference axis or plane.
While these inventions are useful for their intended purposes, they often require extensive modifications to existing equipment. Moreover, when the optic marker is projected onto the workpiece, the tool itself can sometimes obscure the marker as the tool engages the workpiece. This can result in a loss of accuracy as the operator attempts to align the operative component of the tool with the optic marker. Mechanisms used to calibrate the optic marker with a reference axis or plane have limited the applications in which the alignment apparatus can be used or require the use of a tool to carry out the calibration.
Accordingly, there exists a need for an alignment apparatus that is both versatile (i.e., can be used with multiple types of tools, machines, or other devices), and uses laser optics to perform the alignment of the apparatus apart from the workpiece. It is further desired that the alignment apparatus be capable of calibration with respect to a reference axis or plane without requiring additional tools.